(1) Technical Field
The present invention relates to a nanowire sensor, sensor array, and method for making the same. More specifically, the present invention relates to a system and method for the fabrication of a conductometric sensor array comprising nano-sized wires.
(2) Description of Related Art
A molecular sensor system offers many advantages over conventional sensor systems. In addition to allowing dense packing of individual sensors, the molecular nature of such a system allows for the detection of very low concentrations of analyte. For sensors where analyte contacts the sensor surface (non-spectroscopic methods), a change in a characteristic of the surface, such as conductivity, capacitance, temperature, resonance frequency, or color, signals the presence of analyte. In conductometric sensors, response is measured as change in conductivity. Conductometric sensors have been made with a variety of sensing materials, including metals, metal oxides, inorganic semiconductors, polymer-carbon composites, and conducting polymers (including organic semiconductors). The mechanism of conductivity change is not the same in all materials, but in all cases, contact with an analyte results in a change in the conductivity of the sensing material. The change is measured as a change in resistance, measured in voltage.
In array based sensing systems, also known as electronic noses for vapor sensing, the sensors have overlapping sensitivities and the response is read as a pattern across the array. Each sensor responds to compounds in a different degree (or manner) from other sensors, resulting in a pattern of responses unique to each compound. Compounds are then identified using pattern-recognition software designed for that purpose and based on laboratory training sets. The magnitude of responses may be used to quantify the analyte with well-characterized sensor sets.
A desirable technique for designing a highly sensitive conductometric sensor is to make the sensing material as thin as possible. Chemical compounds contacting the surface will change the conductivity of the surface, but in a thick film, such a change may be too small to result in a measurable response. Measurement of the responses in these nanosensor systems requires a specifically designed system.
Therefore, a need exists in the art for a conductometric sensor array that requires little power to operate, is easy to manufacture, and whose size will provide for applicability in areas where space is limited.
Additionally, the growth of nanowires is a complex and high-cost procedure, providing little control over the process or result. Present applications allow for the fabrication of nanowires without the ability to either control their growth or their direction.
Therefore, a need exists in the art for the ability to fabricate a nanowire using a controlled-growth process to actively select the dimensions, positions, and alignments of nanowires.